Process of making a halogenated red dye.



UNITED STATES PATENT OFFICE.

GADIENT ENGI,.OF BASEL, SWITZERLAND, A SSIGNOR TO THE FIRM OF SOCIETY Ol CHEMICAL lNDUSTRY IN BASLE, OF BASEL, SWITZERLAND,

PRooEsseF MAKING A HALOGENATED RED DYE.

Specification of Letters Patent.,

ratenteaotge-a moz- 7 Application filed March 23,1907. Serial No. 364,021.

. To all whom it may concern:

-Be it known that l; GAoInn'r ENGI, doctor of phi- I losophy andchelnist, a citizen of the Swiss Republic,

and exact specification. 10,

and resident of Basel, Switzerland, lave invented a new andmseiul process for the manufacture? of hal0. genated red Vat-dyeing dyestuffs derivcdiroln the co'ndensation product of alpha-oxythionaphthene with an isatin compound, of which theiollovrini is a full, clear,

In my application for Vnited' States Letters Patent Ser. No. 351443 z-filed- January 9th, 1907, I have descrihcil this manufacture of red halogenated at-dyeing dyestuffs bytreatingiwith a halogen, in presence of anindifferent diluent, the condensation productsof equilnolecular quantities of alplia-oxythionaphtlrene v(thicindoxyl) and of an isatin' compound. "Since I have found, that the'chime-derivatives ot'thesaid condensation products canalso b e produced reacting di rectly on the said condensation products with a -1nix-' tnre of concentrated hydrochloric acid and'of concentrated nitricacid. The properties ofthe chlorinated dyestuffs thus ohtainedare thelsa-me as thoseof "the chlorinated product obtained according to Example 11 of my above mentioned application for United Stat-cs Letters Patent Ser. No. 351443] I The new process is illustrated by following ex- I ample: 5 parts of the. product obtained by the condensation of equilnol'ecular quantities of acid salicylthiozu-etieoroi alpha-oxythionaphthene (thioindoxyl) with .during 3 to 5 hours. After cooling the mass of reaction :acid the products resulting from the eomlensation 01' one compound,

isatin are poured into a cold nnxture of ZQJ'pan-t "tr-:

concentrated nitric acid and ch parts of c'oa'iceni trated nnlriatic (hydrochloric) acid and the uthol-eus' warmed on the water bath in a reflux apparatus grad ually to 50 C. and maintained at this temperature is poured into 600 liters water; filtered, washed and dried, the chlorinated product thus obtained being in the forrn of a dull red, crystalline powder. This dyes'tui'f has the saine properties as the product described;

in Example II of rny application forxLettersPatent SCI. No. 351443.

What I claim is;

-"1. The herein described process for the manufacture of red vat-dyeing dyestuffs by treating with amixturc of v concentrated hydrochloric acidhnd of concentrated nitric moi. of aiphaoxythionaphtlicnejwith. one. mo]. of an isatinf 1907, in the presence of two subscribing 

